The present invention relates to a CD player and, more particularly, to a CD player having a stabilizing disk driver mechanism and an optical scanning mechanism having a fixed position optical head. The CD player also incorporates a magazine for holding a plurality of disks. The configuration of the disk driver and optical scanning mechanism permits a compact CD changer size to be achieved, which conforms to DIN dashboard cavity dimensions while providing magazine operation.
Automobiles are presently equipped with dashboard cavities for audio devices with dimensions (182 mm wide, 53 mm high) conforming to a DIN standard (ISO 7736). While these dimensions are sufficient for radios, cassette decks and single CD players, they are insufficient for presently available CD changers. As a result, automotive CD changers must be mounted in a trunk area and connected to a dash mounted controller. Such an arrangement requires additional labor to run connections between the trunk and dash. Furthermore, locating the CD changer in the trunk makes exchanging disks inconvenient. Therefore, there exists a need for an in-dash CD changer that can be installed in DIN standard dashboard cavities.
Primary design considerations determining the compactness of a CD changer include the relationship between playback and storage positions and the construction of the optical scanning mechanism. Japanese laid-open patent publication 2-143942 discloses a device wherein the playback and storage positions of a disk overlap while centers of each position are diagonally opposed within a chassis of the CD changer. Similarly, Japanese laid-open patent publication 3-201259 discloses a device having overlapping storage and playback positions aligned along a centerline of the device. Each of these devices includes an optical head transported along a diagonal of the chassis. Other dash mounted CD players include those disclosed in Japanese patent publication 2-6151 and Japanese patent publication 4-62157, wherein the optical head also moves along an axis inclined relative to the sides of the device.
Each of the above referenced devices has a turntable upon which the disks are rotated during playing. Since the disk is supported solely at its center during the playing, the disk is subject to vibrations and resonances which interfere with the reading of the disk. Such disturbances require that the optical servo focus mechanism operate over a sufficient range to provide compensation. However, not all disturbances can be compensated for and sound quality is degraded as a result of erroneously read data and amplification of the focus servo signal.
Disk reader configurations for reducing vibrations and resonance have been attempted. A Japanese laid-open utility model publication 57-138175 shows a device wherein a disk is supported on a turntable and pressed between drive and idler rollers engaging recorded medium and label surfaces of the disk. The rollers are mounted in conjunction with the optical head and move with the optical head as the disk is scanned. Roller contact is thus maintained in close proximity to a scanning point. Support of the disk at both the center aperture and the rollers limits disk vibrations and resonance at the scanning point. However, the contact made by the rollers with the recorded medium and the label surfaces results in these surfaces becoming damaged. Damage to the label is unsightly and damage to the recorded medium results in erroneous data being read and a consequential loss of sound quality. Furthermore, the disk is supported along a single axis defined by the turntable center and points of contact made by the rollers. The linear support is subject to pivoting type vibrations and resonances.
Further size constraints are encountered in the design of the disk drivers used to rotate the disks during playing. Typically, the disks are rotated by turntables engaging center apertures of the disks. The turntables in the above devices are driven by motors coupled beneath the turntables. Thus, disks must be removed from a storage location a sufficient distance to provide clearance for the turntable to access the center apertures of the disks. Since the turntables are driven by drive motors or drive trains substantially in line with the turntable, the center aperture of a disk being played cannot overlap the other disks held in storage. Therefore, devices having such a turntable drive arrangement must have sufficient dimensions to allow this clearance to be achieved. This necessitates that the center aperture clear disks in the magazine.
In each of the above devices, the compactness of the devices is limited by the space occupied by mechanisms for actuating the optical head, clearance requirements of the disk drive mechanisms, and circuit boards for controlling the mechanisms. Thus, the number of disks held by the devices can not be increased and the depth dimensions of the devices can not be decreased. The depth requirements excluded the possibility of providing a CD changer compatible with the above reference DIN dimensions.